public static int removeDuplicates(int[] nums) {
        if (nums == null || nums.length == 0) {
            return 0;
        }
        if (nums.length == 1) {
            return 1;
        }
        int index = 0;

        for (int i = 1; i < nums.length; i++) {
            if (nums[i] != nums[index]) {
                nums[++index] = nums[i];
            }
        }
        return index + 1;
    }